Background: SkySQL is a distributed company. Nearly all of us work from home. To be productive, we need to emulate the best aspects of collaborating as if we were working next to one another. Given that nearly all of us had worked under similar distributed conditions at MySQL AB, we knew what we were getting into when we were founded. Obviously, we wanted to learn from our past experiences when making our choices for tools and processes.

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This post is about a fairly technical detail of how Galera works. I'm writing it down in preparation for testing this feature so that I can agree with Alex whether to file a bug or not. I'm sharing it on my blog just in case someone else might benefit from learning this.

Galera 2.0 introduces rolling schema upgrades. This is a new way to do non-blocking schema changes in MySQL.

As the name suggests, it is done as a rolling upgrade. Having seen clusters doing rolling upgrades before, I assumed this is what happens:

• Execute alter table on Node 1.
• Node 1 is removed from the cluster and stops processing transactions.
• Node 1 completes alter table.
• Node 1 re-joins cluster and catches up so that it is in sync.

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The slides from last week’s talks I (co-)presented at Percona Live and Linuxcon Europe are now available from our web site.

• In my tutorial MySQL High Availability Sprint: Launch the Pacemaker, I gave a fast walk-through of Pacemaker high availability for MySQL. Tutorial presented at Percona Live UK 2011 in London, England.
• In Fencing and Maintaining Sanity in High Availability Clusters, Madison Kelly and I explored the importance of fencing in HA clusters, highlighted important considerations for fencing, and shared technical details and best practices. Talk presented at Linuxcon Europe 2011 in Prague, Czech Republic. …

If you run (or plan to deploy) high availability clusters — with or without DRBD — you might find a new section on our web site handy. Our Technical Guides collection is a compilation of LINBIT expert HA knowledge, which we’re opening up to everyone.

Yes, this also includes PDF versions of the DRBD User’s Guide and the Linux-HA User’s Guide.

More Technical Guides will be added as we go along. LINBIT Cluster Stack support customers will receive new Tech Guides approximately one month before they pop up on …

Nagios is a powerful monitoring system and here we will learn how to monitor MySQL through Nagios. We will be installing Nagios, required plugins and configuring it to monitor MySQL…

The post 10 Steps: MySQL Monitoring through Nagios: Install & Configure first appeared on Change Is Inevitable.

Every once in a while, we hear of users with corruption in a file system that sits on top of DRBD. That may be easy or tricky to resolve. If you’re lucky, a simple fsck will resolve the corruption. If you’re not quite that lucky, you may have to get out your backups.

But that’s typically not DRBD’s fault. Typically not at all, not in the least bit. DRBD is a block device, and as such it has no idea what rests on top of it. It has no concept of a filesystem, let alone its integrity. That of course is true for any other block device as well. If you have, say, RAID-1, and something corrupts the file system on top of it, then of course that corruption will be happily replicated across both component devices. DRBD is no different, except that its component devices are stored across distinct physical nodes.

And even if everything about your filesystem is logically correct, there’s still the chance that a …

A live recording of my LinuxTag 2010 presentation entitled Storage Done Right: Building a Resilient, Distributed, Highly Available Open Source iSCSI SAN is now available from our web site. If you want to find out how to build a complete SAN from 100% open source, do take a look!

I do apologize for the less-than-optimal sound quality. I did the recording myself with my laptop mike, so unfortunately there’s quite a bit of clipping in the audio track. I hope my ramblings are still somewhat audible.

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Prologue: Long back there were golden days of post graduation in the “great” DDIT (Now Dharamsinh Desai University), Nadiad. Assignments, termwork and journals or everything similar was in demand – I attempted a java code as my termwork on Monday, October 03, 2005. [That’s created date of .java file, I don’t remember anything.] A “variable […]

While Yves presents a valid approach for managing NDB with Pacemaker and the anything Linux-HA resource agent (a generic wrapper for any daemon based application), the XML configuration shown is likely to have people running away screaming. This is how we had to do things back in the Heartbeat 2 days, which meant that as a cluster admin you would permanently run around with a loaded cocked shotgun with the muzzle pressed firmly against your foot.

Those days are long gone. Please don’t do this anymore. You also no longer need to use the low-level tools such as cibadmin or crm_attribute.

We have the crm shell …

I’m hearing a lot of “NoSQL” these days. To really understand how (and) does it works, I decided to give a try on MongoDB. MongoDB (hu*mongo*us) is an open source, scalable, high-performance, schema-free, document-oriented database written in the C++ programming language. MongoDB is not a Relational Database Management System. The database manages collections of JSON […]